It is known in the transmission of digitalized speech information from a transmitter to a receiver to encode and decode on the transmitter side and to decode the speech information on the receiver side in accordance with a linear predictive method. LPC (LPC=Linear Predictive Coding) is an energy-related method of analyzing speech information, that enables good speech quality to be achieved at low bit rates. Linear predictive coding, LPC, generates reliable estimates of speech parameters while being relatively effective calculatively at the same time. The GSM EFR (GSM=Global System for Mobile communication; EFR=Enhanced Full Rate), standards, which improved speech encoding for full rate, constitute an example of linear predictive coding, LPC. This coding enables the receiver of a speech signal, which may have been transmitted by radio for instance, to correct certain types of errors that have occurred in the transmission and to conceal other types of error. The methods of frame substitution and error muting or suppression are described in Draft GSM EFR 06.61, "Substitution and muting of lost frames for enhanced full rate speech traffic channels", ETSI, 1996, and ITU Study Group 15 contribution to question 5/15, "G.728 Decoder Modifications for Frame Erasure Concealment", AT&T, February 1995, based on the standard G.728, "Coding of speech at 16 kbps using Low Delay--Code Excited Linear Prediction (LD-CELP)", ITU, Geneva, 1992 can which are examples of procedures of this kind. For instance, U.S. Pat. No. 5,233,660 teaches a digital speech encoder and speech decoder that operate in accordance with the LD-CELP principle.
Because speech information can be encoded in accordance with alternative coding algorithms, such as pulse code modulation, PCM, for instance, it is known to repeat a preceding data word when an error occurs in a given data word. The article "Waveform Substitution Techniques for Recovering Missing Speech Segments in Packet Voice Communications", IEEE Transactions on Acoustics, Speech and Signal Processing, Vol. ASSP-34, No. 6, December 1986, pp. 1440-1447 by David J. Goodman et al, describes how speech information that has been lost in a PCM transmission between a transmitter and a receiver is replaced on the receiver side with information that has been extracted from earlier received information.
In the case of systems in which speech information is modulated in accordance with adaptive differential pulse code modulation, ADPCM, several methods are known for suppressing errors and restricting high signal amplitudes, wherein the state in decoding filters is modified. M. Suzuki and S. Kubota describe in the article, "A Voice Transmission Quality Improvement Scheme for Personal Communication Systems--Super Mute Scheme", NTT Wireless Systems Laboratories, Vol. 4, 1995, pp. 713-717, a method of damping the received signal in the ADPCM transmission of speech information when data has been transmitted erroneously.